Windows for use primarily in residential structures are available in different styles. Double hung windows, casement windows and slide windows have been installed in many homes for many years. Double hung windows in particular are very popular. They comprise a lower sash window and an upper sash window. The two sash windows are mounted to move vertically alongside one another. More modern double hung windows are also mounted to tilt inwardly about a lower pivot point. This allows access to an exterior surface of the glass for ease of cleaning purposes.
A substantial effort has been expended to create a reliable balance, lock and tilt mechanism for use with the above mentioned double hung windows with tilt capability. The mechanism must allow the sash windows to move up and down with minimal effort by the homeowner. Each of the window sashes must have the capability of remaining at a desired height on its own. The sash windows must also be able to tilt inwardly at any desired window height position. Examples of mechanisms to accomplish the above purposes can be found in U.S. Pat. Nos. 3,844,066, 4,068,406, 4,683,676, 5,210,976, 5,237,775, 5,371,971, 5,383,303 and 5,414,960.
A problem with known balance, lock and tilt mechanisms for double hung sash windows is that the locking or braking action of the mechanisms is less than desired. The homeowner who has tilted one of the sash windows inwardly expects the window to remain in place. Without adequate locking, the window can slide downwardly to create an inconvenience. Also, a certain degree of inadvertent downward force by the homeowner onto the window while cleaning is expected. Known mechanisms provide the locking by friction forces of a brake shoe against the window frame. Different camming actions have been used, all causing a component to move into friction engagement with a surface of the window frame. However, given the size limitations of the mechanisms, necessarily brake shoes have minimal surface areas for friction contact. As a result, known double hung sash windows are prone to moving even after a locking force has been applied and set.
In accord with a need in the original and replacement window industry, there has now been developed a balance shoe assembly with enhanced locking action. The balance shoe assembly is economical to produce. It is adapted for use with commonly used balance mechanisms and in conventional window frames. Most importantly, the balance shoe assembly provides a locking force in excess of those systems presently available.